Study: Cagayan de Oro Ground Water Supply Could Be Approaching Critical Level
Mike Banos
December 29, 2010
Recent updates of a study conducted ten years ago have confirmed fears that Cagayan de Oro City´s ground water supply is fast approaching a critical level which may result to irreversible damage to the city´s aquifers.
During a Dec. 20 public hearing conducted at the city council session hall for a proposed ordinance on raw water pricing, academics from the Ateneo de Manila University (AdMU) and Xavier University (Ateneo de Cagayan) presented new findings which indicate the ground water mining is accelerating the depletion of the city´s aquifers.
Dr. Rosalina Palanca-Tan, Ph.D. of the AdMU´s Department of Economics, presented recent findings and updates on their 2003 Studies "Watershed and Groundwater Depletion in the Philippines: The Cagayan de Oro Experience" and "A Water Permits Scheme for Groundwater Use in Cagayan de Oro."
Tan said the studies conducted in 2001 surveyed the Cagayan de Oro City Water District´s production wells and 184 other deep well owners in Cagayan de Oro to estimate total groundwater abstraction in the city.
In 2001, water abstraction already reached some 114,000 cubic meters per day (cmpd) (77,000 of which was accounted for by the COWD), or 20,000 cmpd (21%) over the safe yield of 94,000 cmpd estimated by the JICA Water Resources Study of the Philippines conducted in 1991.
Dutch Hydrologist Jan Taat presented new findings from an ongoing study he is supervising for Xavier University´s Engineering Resource Center (ERC) that indicate the ground water mining noted by the AdMU Study of 2003 was getting worse.
"From the aquifer properties, a flow to Macajalar Bay of 29-116 million cubic meters (m3) per year is estimated," Taat said. "The groundwater abstraction for water supply in May 2010 was 44 million m3 per year. These abstractions have therefore a major influence on the groundwater availability."
He noted how ground water levels in Barangay Macasandig well field were already 10 meters below sea level
Tan said falling water levels of the city´s deep wells were also indicative that the aquifer´s recharge rate cannot cope with the increasing volume of abstractions, hence the existence of ´ground water mining.´
"We were able to gather some data on the water levels of some 12 deep wells of the water district which show their static water levels have fallen over time," Tan said. "Production Well No 2 in Bgy. Macasandig dropped from 20 feet in 1983 to almost 50 feet in 1995. Production Well No. 10 in Calaanan dropped from 15 ft in 1987 to over 50 feet in 1993. In Bugo, Production Well No. 5 which was initially free flowing in 1989 had already dropped to a static water level of 8 feet below the ground by 1993."
"On the average, static water levels in COWD production wells in Macasandig fell by about 3ft per year, those in Calaanan dropped by 7-14 ft per year and newer ones in Bugo by one foot per year," she added.
Tan said the research team is now updating the estimates and noted the COWD alone had increased its withdrawal to 103,000 cmpd, an increase of 25,000 cmpd (33% increase) despite sourcing an additional 40,000 cmpd from the city´s bulk water supplier starting in 2007.
Tan also noted that the team has identified a number of wells constructed after 2000 while shopping malls and subdivisions mushroomed.
"In 2000, we identified only seven subdivisions with deep wells. At present, there are 32 newly developed subdivisions that are served by deep well operators. Two very big shopping complexes have also emerged," she noted.
However, there appears to be a silver lining to the overall ground water situation. Taat said the Calaanan well field is recovering after the COWD reduced abstractions when it started sourcing processed surface water from its bulk water supplier in 2007.
"We want to allay the fears of the city about the crisis in the ground water supply," said Engr. Joffrey Hapitan, senior vice president of Rio Verde Water Consortium, the COWD´s bulk water supplier. "Even if COWD stops abstracting water from its deep wells, we can deliver 100,000 m3 of potable, processed surface water every day by July 2011 which can more than make up for that shortfall should the city government ban ground water abstraction for say, a period of 10 years to allow our stressed aquifers to safely recover."
Tan clarified that their raw water advocacy is not in any way related to the position of Rio Verde as articulated by Hapitan. Their two previous studies commenced in 2000 before Rio Verde was even established and the update now being conducted is being carried out independently by the AdMU research team.
During a Dec. 20 public hearing conducted at the city council session hall for a proposed ordinance on raw water pricing, academics from the Ateneo de Manila University (AdMU) and Xavier University (Ateneo de Cagayan) presented new findings which indicate the ground water mining is accelerating the depletion of the city´s aquifers.
Dr. Rosalina Palanca-Tan, Ph.D. of the AdMU´s Department of Economics, presented recent findings and updates on their 2003 Studies "Watershed and Groundwater Depletion in the Philippines: The Cagayan de Oro Experience" and "A Water Permits Scheme for Groundwater Use in Cagayan de Oro."
Tan said the studies conducted in 2001 surveyed the Cagayan de Oro City Water District´s production wells and 184 other deep well owners in Cagayan de Oro to estimate total groundwater abstraction in the city.
In 2001, water abstraction already reached some 114,000 cubic meters per day (cmpd) (77,000 of which was accounted for by the COWD), or 20,000 cmpd (21%) over the safe yield of 94,000 cmpd estimated by the JICA Water Resources Study of the Philippines conducted in 1991.
Dutch Hydrologist Jan Taat presented new findings from an ongoing study he is supervising for Xavier University´s Engineering Resource Center (ERC) that indicate the ground water mining noted by the AdMU Study of 2003 was getting worse.
"From the aquifer properties, a flow to Macajalar Bay of 29-116 million cubic meters (m3) per year is estimated," Taat said. "The groundwater abstraction for water supply in May 2010 was 44 million m3 per year. These abstractions have therefore a major influence on the groundwater availability."
He noted how ground water levels in Barangay Macasandig well field were already 10 meters below sea level
Tan said falling water levels of the city´s deep wells were also indicative that the aquifer´s recharge rate cannot cope with the increasing volume of abstractions, hence the existence of ´ground water mining.´
"We were able to gather some data on the water levels of some 12 deep wells of the water district which show their static water levels have fallen over time," Tan said. "Production Well No 2 in Bgy. Macasandig dropped from 20 feet in 1983 to almost 50 feet in 1995. Production Well No. 10 in Calaanan dropped from 15 ft in 1987 to over 50 feet in 1993. In Bugo, Production Well No. 5 which was initially free flowing in 1989 had already dropped to a static water level of 8 feet below the ground by 1993."
"On the average, static water levels in COWD production wells in Macasandig fell by about 3ft per year, those in Calaanan dropped by 7-14 ft per year and newer ones in Bugo by one foot per year," she added.
Tan said the research team is now updating the estimates and noted the COWD alone had increased its withdrawal to 103,000 cmpd, an increase of 25,000 cmpd (33% increase) despite sourcing an additional 40,000 cmpd from the city´s bulk water supplier starting in 2007.
Tan also noted that the team has identified a number of wells constructed after 2000 while shopping malls and subdivisions mushroomed.
"In 2000, we identified only seven subdivisions with deep wells. At present, there are 32 newly developed subdivisions that are served by deep well operators. Two very big shopping complexes have also emerged," she noted.
However, there appears to be a silver lining to the overall ground water situation. Taat said the Calaanan well field is recovering after the COWD reduced abstractions when it started sourcing processed surface water from its bulk water supplier in 2007.
"We want to allay the fears of the city about the crisis in the ground water supply," said Engr. Joffrey Hapitan, senior vice president of Rio Verde Water Consortium, the COWD´s bulk water supplier. "Even if COWD stops abstracting water from its deep wells, we can deliver 100,000 m3 of potable, processed surface water every day by July 2011 which can more than make up for that shortfall should the city government ban ground water abstraction for say, a period of 10 years to allow our stressed aquifers to safely recover."
Tan clarified that their raw water advocacy is not in any way related to the position of Rio Verde as articulated by Hapitan. Their two previous studies commenced in 2000 before Rio Verde was even established and the update now being conducted is being carried out independently by the AdMU research team.
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